在ADO中(VC)Recordset如何使用Addnew添加记录？
我想给Recordset添加记录，有两种字段，adVarWChar、adInteger，如何操作？最好有一段详细代码。
另外，我在一个Table中将一个字段设为Primary Key,Unique,该字段为adVarWChar型，我的本意是不允许有重复值，但如果在运行中在Addnew中加入一个已存在的值，会出现什么情况，应如何处理？
问题点数：50、回复次数：3Top
1 楼strip（阿飞 - Mozilla●CSDN●痛）回复于 2002-03-20 08:24:46 得分 50
AddNew Method Example (VC++)
[This is preliminary documentation and subject to change.]
This example uses the AddNew method to create a new record with the specified name.
// BeginAddNewCpp
#import "C:\Program Files\Common Files\System\ADO\msado15.dll" \
no_namespace rename("EOF", "EndOfFile")
#include <ole2.h>
#include <stdio.h>
#include "conio.h"
#include "AddNewX.h"
//Function declaration
inline void TESTHR(HRESULT x) {if FAILED(x) _com_issue_error(x);};
void AddNewX(VOID);
void PrintProviderError(_ConnectionPtr pConnection);
///////////////////////////////////////////////////////////
// //
// Main Function //
// //
///////////////////////////////////////////////////////////
void main()
{
HRESULT hr = S_OK;
if(FAILED(::CoInitialize(NULL)))
return;
if (SUCCEEDED(hr))
{
AddNewX();
//Wait here for the user to see the output
printf("Press any key to continue...");
getch();
::CoUninitialize();
}
}
///////////////////////////////////////////////////////////
// //
// AddNewX Function //
// //
///////////////////////////////////////////////////////////
VOID AddNewX(VOID)
{
// Define ADO object pointers.
// Initialize pointers on define.
_RecordsetPtr pRstEmployees = NULL;
_ConnectionPtr pConnection = NULL;
//Define Other variables
IADORecordBinding *picRs = NULL; //Interface Pointer declared.(VC++ Extensions)
CEmployeeRs emprs; //C++ class object
HRESULT hr = S_OK;
//Replace Data Source value with your server name.
_bstr_t strCnn("Provider=sqloledb;Data Source=MyServer;Initial Catalog=pubs;User Id=sa;Password=;");
_bstr_t strId;
_bstr_t strMessage;
try
{
//Open a connection
TESTHR(pConnection.CreateInstance(__uuidof(Connection)));
pConnection->Open(strCnn,"","",adConnectUnspecified);
//Open employee table
TESTHR(pRstEmployees.CreateInstance(__uuidof(Recordset)));
//You have to explicitly pass the Cursor type and LockType to the Recordset here
pRstEmployees->Open("employee",_variant_t((IDispatch *) pConnection, true),adOpenKeyset,adLockOptimistic,adCmdTable);
//Open an IADORecordBinding interface pointer which we'll use for Binding Recordset to a class
TESTHR(pRstEmployees->QueryInterface(__uuidof(IADORecordBinding),(LPVOID*)&picRs));
//Bind the Recordset to a C++ Class here
TESTHR(picRs->BindToRecordset(&emprs));
// Get data from the user.The employee id must be formatted as
// first,middle and last initial,five numbers,then M or F to
// signify the gender.For example,the employee id for
// Bill A. Sorensen would be "BAS55555M".
printf("Enter Employee Id: ");scanf("%s",emprs.m_sz_empid);
strId = emprs.m_sz_empid;
printf("Enter First Name: ");scanf("%s",emprs.m_sz_fname);
printf("Enter Last Name:");scanf("%s",emprs.m_sz_lname);
//Proceed if the user actually entered some thing
//for the id, the first and the last name.
if(strcmp(emprs.m_sz_empid,"") && strcmp(emprs.m_sz_fname,"") && strcmp(emprs.m_sz_lname,""))
{
//This adds a new record to the table
//if (FAILED(hr = picRs->AddNew(&emprs)))
//_com_issue_error(hr);
TESTHR(picRs->AddNew(&emprs));
//Show the newly added data
printf("New Record: %s %s %s \n",\
emprs.lemp_empidStatus == adFldOK ? emprs.m_sz_empid : "<NULL>",\
emprs.lemp_fnameStatus == adFldOK ? emprs.m_sz_fname : "<NULL>",\
emprs.lemp_lnameStatus == adFldOK ? emprs.m_sz_lname : "<NULL>");
}
else
printf("Please enter an employee id, first name and last name.\n");
//Delete the new record because this is a demonstration.
pConnection->Execute("DELETE FROM EMPLOYEE WHERE emp_id = '"+strId+"'",NULL,adCmdText);
//Release the IADORecordset Interface here
if (picRs)
picRs->Release();
// Clean up objects before exit.
pRstEmployees->Close();
pConnection->Close();
}
catch(_com_error &e)
{
// Notify the user of errors if any.
_variant_t vtConnect = pRstEmployees->GetActiveConnection();
// GetActiveConnection returns connect string if connection
// is not open, else returns Connection object.
switch(vtConnect.vt)
{
case VT_BSTR:
printf("Error:\n");
printf("Code = %08lx\n", e.Error());
printf("Message = %s\n", e.ErrorMessage());
printf("Source = %s\n", (LPCSTR) e.Source());
printf("Description = %s\n", (LPCSTR) e.Description());
break;
case VT_DISPATCH:
PrintProviderError(vtConnect);
break;
default:
printf("Errors occured.");
break;
}
}
}
///////////////////////////////////////////////////////////
// //
// PrintProviderError Function //
// //
///////////////////////////////////////////////////////////
VOID PrintProviderError(_ConnectionPtr pConnection)
{
// Print Provider Errors from Connection object.
// pErr is a record object in the Connection's Error collection.
ErrorPtr pErr = NULL;
long nCount = 0;
long i = 0;
if( (pConnection->Errors->Count) > 0)
{
nCount = pConnection->Errors->Count;
// Collection ranges from 0 to nCount -1.
for(i = 0; i < nCount; i++)
{
pErr = pConnection->Errors->GetItem(i);
printf("\n\t Error number: %x\t%s", pErr->Number, (LPCSTR)pErr->Description);
}
}
}
// EndAddNewCpp
AddNewX.h:
// BeginAddNewH
#include "icrsint.h"
//This Class extracts empid, fname and lastname
class CEmployeeRs : public CADORecordBinding
{
BEGIN_ADO_BINDING(CEmployeeRs)
//Column empid is the 1st field in the recordset
ADO_VARIABLE_LENGTH_ENTRY2(1, adVarChar, m_sz_empid,
sizeof(m_sz_empid), lemp_empidStatus, TRUE)
ADO_VARIABLE_LENGTH_ENTRY2(2, adVarChar, m_sz_fname,
sizeof(m_sz_fname), lemp_fnameStatus, TRUE)
ADO_VARIABLE_LENGTH_ENTRY2(4, adVarChar, m_sz_lname,
sizeof(m_sz_lname), lemp_lnameStatus, TRUE)
END_ADO_BINDING()
public:
CHAR m_sz_empid[10];
ULONG lemp_empidStatus;
CHAR m_sz_fname[40];
ULONG lemp_fnameStatus;
CHAR m_sz_lname[41];
ULONG lemp_lnameStatus;
};
// EndAddNewH
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2 楼strip（阿飞 - Mozilla●CSDN●痛）回复于 2002-03-20 08:25:37 得分 0
Table中将一个字段设为Primary Key,Unique,该字段为adVarWChar型，我的本意是不允许有重复值，但如果在运行中在Addnew中加入一个已存在的值，会出现什么情况
:
update的时候回抛出异常，你最好自己试一下就清楚怎么回事了Top
3 楼pfans（pfans）回复于 2002-03-20 08:37:53 得分 0
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